1. Field
The disclosure relates to techniques for increasing power efficiency in a switched-mode power converter.
2. Background
Buck converters are a type of switched-mode power converter designed to efficiently step down a supply voltage, e.g., a battery voltage of a system, from a first level to a second lower level. A buck converter typically includes a high-side switch and a low-side switch configured to alternately couple an inductor to an output voltage or ground. The high-side and low-side switches may be configured to drive the output voltage to a predetermined target output voltage using a plurality of schemes known in the art, e.g., pulse-width modulation (PWM), pulse-frequency modulation (PFM), etc.
In a PFM mode of operation, the high-side and low-side switches are configured to vary the frequency of a train of pulses that charge and discharge the inductor. In PFM, there are at least two sources of power losses affecting the efficiency of the buck converter circuit. First, turning the switches on and off to generate the train of pulses leads to “switching losses,” due to the current required to charge and discharge various capacitances in the switches. Second, sinking or sourcing DC current through the switches leads to “conduction losses,” arising from the finite on-resistance of the switches themselves. Together, such losses undesirably decrease the power efficiency of the buck converter circuit as well as other types of switched-mode power converters.
It would be desirable to provide techniques for optimizing the operation of a switched-mode power converter such as a buck converter employing high-side and/or low-side switches to improve the overall power efficiency of the circuit.